Fatslinger suggested wiring a can with electricity. I would not suggest it, but if I did something like that, I would use an electric fence device as the source of power.
It calls to mind a story that a fellow told me about his experience as a summer employee at Yellowstone National Park many years ago. They housed at a barrack quite remote from the regular park visitors, and had bears regularly visit their garbage cans (this was many years ago). They used "available power" to electrify a screen on which the can was placed. They had a number of bear visits were adequately discouraged by the jolt delivered.
Then one night they heard an awful ruckus. They came out to find a corpse of a large, soaking wet bear next to the garbage can. This poor animal had just come across a nearby river, and was made especially electrically conductive.
They had to drag this large animal away to hide the evidence of their misdeed.
The best laid plans of mice and men...
